1) Field of the Invention
The present invention relates to a system for identifying the location of a vehicle through modeling the vehicle path and the wayside, and more particularly modeling a train on a track.
2) Description of the Prior Art
Until recently, identifying the location of a train on a train track was an inexact science. Specifically, a train track was divided into fixed sections known as blocks. Once a particular train entered a block, no other trains could enter that block since the exact location of the train was unknown.
The "fixed blocks" can vary in length from hundreds of feet to miles on a particular track. In many instances, the fixed block arrangement adversely affects a train's schedule by preventing a train to enter a block even though it is a safe distance from the next closest train that just happens to be located in that block.
Recently, the concept of a "moving block" has been proposed. A moving block system is a dynamic system which creates an imaginary space or block that moves along with a particular vehicle as it travels along a track where no other train or vehicle may enter that space. The length of the moving block depends on various characteristics, such as train speed, train braking ability, etc. A simple example of a moving block is a space which extends one hundred feet in front of and one hundred feet behind a particular train. Through appropriate communication devices and computers, the appropriate safe distance between trains can be continuously calculated and this safe distance can then be identified as the moving block that moves along with the train. The length of the moving block varies as the operating parameters of the train change.
A train system implementing the moving block system requires an onboard computer for each train and one or more wayside computers to communicate with the trains. A problem in implementing this moving block technology into large scale train systems is the size of the computers necessary to operate and communicate to the trains. Another major problem in a train system, be it a subway train system or a large scale interstate train system, is how to identify the location of the train. Each train system identifies a vehicle location differently. Therefore, a problem exists in automatic train control systems as to how train positions can be identified universally, be it in a New York subway or in a train system for a train traveling across the United States.
Further, prior art methods that model the track and the wayside typically require several databases to model the wayside, such as a database for maximum civil speed, track grade, etc. This requires a substantial amount of computer memory and results in relatively slow processing time when monitoring a vehicle on a vehicle pathway modeled via all of these databases.
Therefore, it is an object of the present invention to provide a universal communication based vehicle positioning reference system.
It is another object of the present invention to provide a vehicle positioning system that can operate through a plurality of computers rather than one central computer.
It is yet another object of the present invention to provide an improved model of a vehicle system.